This type of thermal utilization systems has been reported in, for example Japanese Patent Publication 58-19955, Japanese Patent Publication No. 61-20205, in which two kinds of hydrogen absorbing alloys are utilized in such a way that one of them is heated at an operating temperature of 130.degree. C..about.150.degree. C. to dissociate the hydrogen, which is transported to the other alloy and absorbed by this alloy exothermically, and endothermical reaction heat at returning the hydrogen provide refrigeration.
However, these conventional systems have difficulty in that they require high operating temperatures in the range of 130.degree. C..about.150.degree. C., which is too high for such thermal system as utilizes a cogeneration system, factory waste heat, or solar heat as an operating heat source, so that desirable operating efficiency cannot be gained.
Other prior art such as Japanese Patent Publications Nos. 62-1188 and 62-1189 disclose similar refrigeration systems, which, however, have difficulty in that alloys must be heated so as to make the operating pressure of hydrogen, required for the absorption of the hydrogen dissociated from one alloy to the other, to exceed 20 atm. This implies that the container must be designed pressure-proof, resulting in a structural complexity of the container and accompanying sensible heat loss.